How far away is our moon from our planet? How long ago were dinosaurs walking the Earth? What is the atomic composition of water? These are questions with answers, and they are answers that were at some point placed into a book and handed out in classrooms. We used to get our facts from similar sources; our teachers, our parents, and our community. Now though if I happened to think that the Earth was flat I need only look to the wealth of information online confirming my belief. What compounds the problem with trying to filter the masses of data is that the algorithms responsible for our information diet tend to figure out that we really like cake, and decide that infinite cake it is.
When we are all having our own views constantly affirmed we look at somebody being given a completely different subset of the onslaught of opinions as though they were from a different planet. Indeed, how does one relate to another human when you can't even agree on the truth of what's in the water supply? As we've seen, most of the time you just don't bother, you ignore the other morons who don't even realise that 9/11 was so obviously a hoax and you stay in your little world of conspiracy theorists.
The polarisation has clearly manifested itself in some extreme ways, but even the moderate outcomes have had an enormously damaging impact on society. The role played by social networks in the 2016 Presidential election has been discussed to death, and living in our own world of facts really isn't the only reason that the election went the way that it did, but it's definitely the reason that it shocked so many of us. With barely any exposure to the other side each was equally certain that they were "winning".
Tristan Harris has been described by The Atlantic as the "closest thing Silicon Valley has to a conscience" and has dedicated a lot of energy to pointing out the dangers in not taking seriously the impact that these algorithms can have on our psyche. Another such dissenting voice from within the Valley is Jaron Lanier. The ideas and arguments are out there, whether or not we can get these now trillion dollar companies to listen is another matter, but it's certainly within their interests as well as our own.